Semiconductor devices generate heat during operation, and this heat usually acts to degrade the operation of the semiconductor device. For power semiconductor devices, heat removal may prove beneficial to maintain acceptable device performance. Large power semiconductors often consist of a high number of silicon chips or dies connected in series or parallel, depending on the use, and may be attached to a common board. Such large power semiconductors are often called power modules.
Liquid cooling of power semiconductors often involves having a heat sink attached to the bottom of the power semiconductor module, i.e. the base plate of the module. The heat sink contains a closed circuit for a liquid coolant that may include inlet(s) and outlet(s) for providing fluid connections to a heat exchanger. This method is known as indirect cooling.
Direct cooling of power semiconductor modules is also practiced, and involves a chamber for the liquid coolant defined in a basin of the heat sink. The base plate of the power semiconductor module may be attached to the heat sink over the basin, effectively acting as a lid to cover the basin and placing the coolant in the basin in thermal contact with the base plate for heat removal therefrom. Fasteners, such as bolts or screws, are often used to secure the heat sink and base plate.
The actual flow and/or heat transfer of the liquid coolant can be made in many different ways, one way is by using a distributing element, which is inserted in the basin, and another known way is by having an array of cooling fins protruding from the base plate into the liquid coolant. Such a distributing element is disclosed in EP 2207201.